Works carried out in the field of space balloons have led to the development of balloons of a generally cylindrical form for supporting very high over-pressures. In effect, support of the over pressure on the ends of the cylinder is assured by the simultaneous effect of three actions: the action of the envelope itself, the action of an inter-polar connection connecting the two poles of the envelope, and the action of an external network of longitudinal reinforcements. The ability of the cylindrical wall to support the over-pressure is assured by the provision of longitudinal lobes separated by a network of circumferential reinforcements, additionally assuring the taking up of the radial component of the longitudinal tension. Proven methods of calculation permit, in each application, the adjustment of the different parameters (density of the circumferential network, density of the longitudinal network . . . ) in such a manner as to optimize the range of constraints applicable to the envelopes. The mastery of these different parameters thus permits obtaining flexible envelopes of very high over pressure in which the forming material (with assymetrical resistance higher in the longitudinal direction than in the circumferential direction) works in the optimum conditions--that is to say in each direction, its elastic limit multiplied by a coefficient of safety.
In fact, at the present time, the primary difficulties remaining relate to the hooking of the extremities of an envelope to the pole pieces, necessitating particular consideration for resolving the problems of the interface between the flexible structure and the rigid structures to be supported, such problems presenting very important constraints. The different hooking devices available necessitate in practice over-dimensioning of the pole pieces because of the significant torque to which the pole pieces are subjected. Moreover, and in particular, these devices require the provision of a locking flange on the extreme edge of the envelope. Further, the geometric definition of the flange being rarely perfect, different strands forming the longitudinal warp of the envelope are subjected to different longitudinal stresses, and this leads to the creation of sheer forces, which are difficult to quantify.
The present invention proposes to furnish a process for hooking or securing an envelope to a fixation piece, which permits taking up or bearing significant forces, while assuring the gas-tight seal of the envelope, and which solves the problems discussed above.
To this effect, an essential object of the invention is to provide a process for hooking an envelope permitting the homogenization of the constraints in the different strands forming the longitudinal warp of the envelope.
Another object of the invention is to reduce the intensity of the torsional stresses to which the fixation pieces are subjected.
Another object of the invention is to provide a process enabling a simplification of, and making very precise, the different operations involved in hooking an envelope to a fixation piece.
Another object of the invention is to permit controlling the hooking characteristics, before the filling of the envelope.
Another object is to provide a process for hooking onto a fixation piece the external longitudinal reinforcements permitting the transmission of torque tending to rotate the envelope.